ESUS is defined as a visualized non-lacunar brain infarct in the absence of a) extracranial or intracranial atherosclerosis causing ≥50% luminal stenosis in arteries supplying the area of ischaemia, b) major-risk cardioembolic source, and c) any other specific cause of stroke (e.g. arteritis, dissection, migraine/vasospasm, drug misuse). Major risk sources of cardioembolism include permanent or paroxysmal atrial fibrillation, sustained atrial flutter, intracardiac thrombus, prosthetic cardiac valve, atrial myxoma or other cardiac tumours, mitral stenosis, recent (<4 weeks) myocardial infarction, left ventricular ejection fraction less than 30%, valvular vegetations, or infective endocarditis.